Radio transmitting apparatus



June 3 1924.

P. LAUT RADIO TRANSMITTING APPARATUS Filed Oct. 18, 1920 Patented June 3,}924.

PAUL LA'UT, on

star A PARIS, FRANCE.

RADIO TRANSMITTING APPARATUS.

Application filed October 18, 1920.

To all whom it may concern Be it known that 1, PAUL LAi'rr, a resident of 79 Boulevard de Montmorency, Paris, France, have invented new and useful improvements in Radio Transmitting Apparatus (for which I have filed applica tions for patents in France, October23, 1919, granted May 3, i 1920, under No. 505,328; Belgium, July 30, 1920, allowed August 14:, 1920, No. 289,694, and Germany, August 10, 1920), of which the following is a specification.

At radio-telegraphic stations using a continuous sequence of waves generated by an are, sending isat present generally acco1nplished by means of a device the diagram of which is indicated, for illustrative pur-. poses in Figure 1 of the attached drawing, and which consists in an arrangement intended to produce larger or smaller variations in the length of the waves emitted by a variation in the inductance of the antenna.

In order to remove the disadvantage of the compensating wave which results from the employ of this device, different systems have been proposed; the best known is the back shunt system, which consists in substituting for the antenna, by means of a special sender, an equivalent circuit possessing inductance, resistance, and capacity;

Other methods, derived more or less from the above, have been proposed and tried.

Besides the disadvantage which they have of not improving the general ei'liciency of the are, which consumes almost the same amountof energy during the signals as it consumes during the interval between sig nals, all these systems necessitate a cumbersome and costly equipment; they have a delicate and unstable adjustment and do not always give signals as clear as the ordinary sending device with compensating wave.

The object of the present invention is the provision of a new sending device which obviates all these disadvantages.

It enables all current in the antenna to be completely suppressed between signals; it gives perfectly clear signals; it improves the efficiency of the arc during transmis sion of a continuous dash, and the general efiiciency of the arc in sending; the power consumed between two signals being greatly reduced, capable of falling to a value of of the energy consumed during transmis- Serial No. 417,554.

sion of a dash. In order to obtain the desired object, a few accessories are in ac cordance with my invention added to the ordinary arc circuit.

In the drawing, Figure l is a diagram of a radio transmitting apparatus showing the sender or key connected in the inductance of the antenna.

Figure 2 is a similar view of a radio transmitting apparatus arranged in accordance with my invention and showing'the sender arranged in connection between the antenna and are. r

In the diagrams Figure 1 and Figure the letters have the following designations:

G, direct current generator; C, C protective condensers; L,, C,, L,, C protectivc oscillating circuits tuned on the oscillating circuit constituted by L C and the electrodes N N N, anode; N cathode; A A protective choke coils; R, rheostat; 5%,. S magnetic blow-out coils energized by direct current from a generator D, or from any other suitable source; M, sender or signaling key; S, antenna inductance; A, antenna.

The condensers C C, the circuits L 0,, L 0,, the choke coils A A may be omitted if the generator is designed for supporting the high frequency excess voltages produced by the operation of the arc.

The resistance R duced to zero.

The capacity has a value which is of the order of the magnitude of the capacity of the antenna, and, preferably, included be tween zero and two times the value of the latter, according to the power of the arc and the electric characteristics of the antenna.

The circuit N N C L has a wave length preferably short; for example, a harmonic of the wave emitted by the antenna may be taken.

The value of the current in the blow-out coils is, preferably, fixed and regulated to a constant value, independent of the value of the current supplied to the arc.

The operation of the system thus defined is as follows:

The antenna being out of circuit and the sender M being open, damped oscillations are produced in the circuit N, N L C when the arc is lighted; L and C are adjusted so that the arc operates with a maximum distance between and N for the supply may eventually here voltage used and the normal blow-out field, that is to say, the lield corresponding to the length of the transmission wave and the power of the transmission.

The are electrodes are then brought slightly closer to each other and the arc is ready for transmission. By pressing on the signalling key, the antenna is connected to the arc; there is an emission of continuous waves, as in the ordinary arrangement. When the signalling key is no longer pressed down, the oscillations disappear spontaneously in the antenna and the arc continues to operate on the auxiliary circuit, 'L C.

The adjustment indicated above permits maintaining indefinitely the arc in operation on the auxiliary circuit, the antenna being open.

It may be useful, particularly for high power equipments, to work with difi'erent adjustment of the arc length, the supply voltage, etc., during emission on the antenna, so as "to improve the eihciency and to increase the power brought into action.

Under these conditions of high efliciency, the arc is extinguished if the antenna remains open for longer than a few seconds.

In order to prevent this extinguishing, theflvar'ious elements oi the installation may be brought as hereinbefore stated to the value 'which permits maintaining indefinite ly the are operating on the auxiliary circuitL C. I I

It is now apparent that by means of the sending device described above, the amount of energy nec l'ssary to maintain the arc between the signals may be reduced to a very low value, and, in consequence, a considerable improveinentin the efficiency of the arc may beobtained, this efficiency being expressed by the ratio of the power supplied.

to the antenna, during the signal, to the average power absorbed by the arc durin b the period of sending.

The use of this device gives, besides, a notable improvement in the clearness and purity of the signals. It permits the increasing of the number of radio-telegraphic stations working simultaneously between the given limits of wave length, and gives a greater facility for the reading or the recording of the signals at the receiving end.

In an existing installation, this device thus permits, with the machines and apparatus in service, the increase of the power of the signals, while in the establishment of a new station, it makes possible the reduction of the size of the generating machines for the same power required in the antenna.

Having novy particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is Sending station applicable to radio telegraphic systems of the known are type, in which the arc is directly connected in the antenna while the throttle coils are excited from an independent source and which device permits to annul completely the current in the antenna in the interval separating the signals, and to suppress in this way the disadvantage of the compensation wave, said device, comprising'a signaling key inserted directly into the antenna, together with an auxiliary circuit formed by an in ductance and a condenser in series, connected permanently between the electrodes of the arc,said auxiliary circuit being effective to. avoid the killing of the arc during the signals.

In witness whereof I affix my signature.

PAUL LAI'iT.

Witnesses:

JASPER MAY, P. A. WATTS. 

